content: /**
   * Copyright (c) 2016-present, RxJava Contributors.
   *
   * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in
   * compliance with the License. You may obtain a copy of the License at
   *
   * http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software distributed under the License is
   * distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See
   * the License for the specific language governing permissions and limitations under the License.
   */
  
  package io.reactivex.flowable.internal.operators;
  
  import java.util.concurrent.Callable;
  import java.util.concurrent.atomic.AtomicLong;
  
  import org.reactivestreams.*;
  
  import io.reactivex.common.*;
  import io.reactivex.common.exceptions.Exceptions;
  import io.reactivex.common.functions.*;
  import io.reactivex.flowable.Flowable;
  import io.reactivex.flowable.internal.subscriptions.*;
  import io.reactivex.flowable.internal.utils.BackpressureHelper;
  
  public final class FlowableGenerate<T, S> extends Flowable<T> {
      final Callable<S> stateSupplier;
      final BiFunction<S, Emitter<T>, S> generator;
      final Consumer<? super S> disposeState;
  
      public FlowableGenerate(Callable<S> stateSupplier, BiFunction<S, Emitter<T>, S> generator,
              Consumer<? super S> disposeState) {
          this.stateSupplier = stateSupplier;
          this.generator = generator;
          this.disposeState = disposeState;
      }
  
      @Override
      public void subscribeActual(Subscriber<? super T> s) {
          S state;
  
          try {
              state = stateSupplier.call();
          } catch (Throwable e) {
              Exceptions.throwIfFatal(e);
              EmptySubscription.error(e, s);
              return;
          }
  
          s.onSubscribe(new GeneratorSubscription<T, S>(s, generator, disposeState, state));
      }
  
      static final class GeneratorSubscription<T, S>
      extends AtomicLong
      implements Emitter<T>, Subscription {
  
          private static final long serialVersionUID = 7565982551505011832L;
  
          final Subscriber<? super T> actual;
          final BiFunction<S, ? super Emitter<T>, S> generator;
          final Consumer<? super S> disposeState;
  
          S state;
  
          volatile boolean cancelled;
  
          boolean terminate;
  
          boolean hasNext;
  
          GeneratorSubscription(Subscriber<? super T> actual,
                  BiFunction<S, ? super Emitter<T>, S> generator,
                  Consumer<? super S> disposeState, S initialState) {
              this.actual = actual;
              this.generator = generator;
              this.disposeState = disposeState;
              this.state = initialState;
          }
  
          @Override
          public void request(long n) {
              if (!SubscriptionHelper.validate(n)) {
                  return;
              }
              if (BackpressureHelper.add(this, n) != 0L) {
                  return;
              }
  
              long e = 0L;
  
              S s = state;
  
              final BiFunction<S, ? super Emitter<T>, S> f = generator;
  
              for (;;) {
                  while (e != n) {
  
                      if (cancelled) {
                          state = null;
                          dispose(s);
                          return;
                      }
  
                      hasNext = false;
  
                      try {
                          s = f.apply(s, this);
                      } catch (Throwable ex) {
                          Exceptions.throwIfFatal(ex);
                          cancelled = true;
                          state = null;
                          onError(ex);
                          dispose(s);
                          return;
                      }
  
                      if (terminate) {
                          cancelled = true;
                          state = null;
                          dispose(s);
                          return;
                      }
  
                      e++;
                  }
  
                  n = get();
                  if (e == n) {
                      state = s;
                      n = addAndGet(-e);
                      if (n == 0L) {
                          break;
                      }
                      e = 0L;
                  }
              }
          }
  
          private void dispose(S s) {
              try {
                  disposeState.accept(s);
              } catch (Throwable ex) {
                  Exceptions.throwIfFatal(ex);
                  RxJavaCommonPlugins.onError(ex);
              }
          }
  
          @Override
          public void cancel() {
              if (!cancelled) {
                  cancelled = true;
  
                  // if there are no running requests, just dispose the state
                  if (BackpressureHelper.add(this, 1) == 0) {
                      S s = state;
                      state = null;
                      dispose(s);
                  }
              }
          }
  
          @Override
          public void onNext(T t) {
              if (!terminate) {
                  if (hasNext) {
                      onError(new IllegalStateException("onNext already called in this generate turn"));
                  } else {
                      if (t == null) {
                          onError(new NullPointerException("onNext called with null. Null values are generally not allowed in 2.x operators and sources."));
                      } else {
                          hasNext = true;
                          actual.onNext(t);
                      }
                  }
              }
          }
  
          @Override
          public void onError(Throwable t) {
              if (terminate) {
                  RxJavaCommonPlugins.onError(t);
              } else {
                  if (t == null) {
                      t = new NullPointerException("onError called with null. Null values are generally not allowed in 2.x operators and sources.");
                  }
                  terminate = true;
                  actual.onError(t);
              }
          }
  
          @Override
          public void onComplete() {
              if (!terminate) {
                  terminate = true;
                  actual.onComplete();
              }
          }
      }
  }
  